CHAPTER 19 WILDLIFE
As humans continue to encroach on previously undisturbed and pristine wild habitats, the frequency of wildlife-human encounters has increased. These increased encounters have led to an increased need for veterinary participation in managing sick and injured animals. For much of the public, veterinarians are still held in reverence because of the James Herriott stories. We believe that it is important for veterinarians to maintain this image. This does not necessarily suggest that veterinarians should consider themselves experts on all animal species, but that as professionals, they should develop an infrastructure of resources that enables them to provide medical and surgical care for those animals in need. In addition, because many of these animals can serve as reservoirs for zoonotic diseases, veterinarians can play an important role in minimizing the risk of disease transmission between wildlife and concerned citizens. For some veterinarians, their role may require them to maintain a current list of veterinarians or wildlife rehabilitators capable of managing an injured wildlife patient and refer clients to these professionals. For others with a more invested interest, it may mean that they will pursue available resources to develop the knowledge and skill for managing these animals in their hospital. The last thing clients, or prospective clients, want to hear from veterinarians is “We don’t work with those animals.” Instead, if veterinarians can, at a minimum, direct clients to the most appropriate resource, veterinarians maintain (and justify) their image among the professions.
There are many financial, ethical, and emotional issues for veterinarians to consider when deciding whether to accept wildlife cases to their practice. Wildlife is not owned and therefore do not come with paying caretakers. In many cases, the hospital will be expected to absorb the cost of treatment, although avenues for monetary compensation, including grants and public donations, do exist. Accepting wildlife cases is often perceived by (prospective) clients as a positive reinforcement of a veterinarian’s compassion toward animals and can serve, directly or indirectly, as a method of increasing a veterinarian’s domestic and exotic pet caseload. One ethical consideration to make with these cases is deciding when intervention may interfere with a natural process occurring in a population. In some cases, euthanasia will certainly end suffering, whereas in others treatment may interfere with both natural selection and the disease status in a population. However, because the lives of humans have become so enmeshed with populations of wild animals, it is unavoidable that some, if not most, of the injuries or disease processes occurring in wildlife populations are the direct result of human contact. In these cases, there may be a strong moral (ethical) obligation to repair damage caused by the human species. An early and rational assessment of the likely return to function for a patient is imperative to conserve the available resources for treatment and prevent undue suffering in the patient. Animals who are considered poor candidates for release or placement should be considered for euthanasia as soon as an assessment is made. Release candidates should be able to function appropriately within their natural habitat (including reproduction) and with conspecifics; otherwise, a disservice is rendered to both the animal and its population.
Certain factors should be weighed before deciding to accept wildlife cases to a practice. These factors should be considered with every case as well. The potential costs include those welfare expenses associated with captivity, treatment, release, and failure to reestablish the animal in the wild, as well as the welfare risks to conspecifics and other species through the possible introduction of infection or competition for resources and the upset in natural selection (e.g., treating animals that have increased susceptibility to disease may inadvertently select for less fit animals). The potential benefits associated with working with these animals include the emotional pleasure humans derive from helping a “lesser” species, the potential to educate the public, and the opportunities this type of medicine provides for monitoring threats to wildlife and human populations.
Assessing the balance or inherent value between welfare costs and benefits is often difficult. In addition to the unpredictability of responses between individual cases to treatment, there are few robust yardsticks for use in judging, for example, whether any stress or pain associated with captivity and treatment does or does not outweigh the potential welfare benefit to the animal. The task is not made easier by the scarcity of information on outcomes of wildlife rehabilitation cases, although more studies are being done. Veterinarians have an important role in these ethical assessments and in helping to design protocols that will best manage the welfare of these animals in both captive and wild settings.
Veterinarians working with wildlife should become familiar with the regulations addressing the handling, transport, and treatment of these animals. These regulations have been enacted at the federal and state levels to ensure the protection of these animals against individuals that would otherwise exploit them (e.g., meat or fur). Historically, veterinarians were perceived as “good Samaritans,” and it was just accepted that veterinarians would or could provide any medical and surgical care that a particular wildlife patient required. Unfortunately, some veterinarians, like many unlicensed wildlife rehabilitators, will attempt to complete the rehabilitation process for their wildlife patients, even though they cannot meet their patient’s husbandry, nutritional, or posttreatment rehabilitation needs. Currently, federal and state governments are committed to maintaining veterinarians as an integral component to the care of injured wildlife and consider veterinarians to be the experts for providing medical and surgical care for these animals. However, these agencies also realize that most veterinarians do not have the time or facilities to fully rehabilitate injured wildlife. Because of this, federal and state agencies require veterinarians (without state and/or federal rehabilitation permits) to transfer these animals to licensed rehabilitators to complete the rehabilitation process. It is expected that a veterinarian will transfer any wildlife patient to a licensed wildlife rehabilitator within 24 hours of stabilizing the patient. A stabilized patient is one that is no longer in dire need of veterinary medical care. Patients that require medical treatment that can be administered via an experienced (trained) rehabilitator should be transferred.
The federal government is primarily invested in the protection of migratory birds and all other species that are listed federally as species of special concern, threatened, or endangered. State agencies also require rehabilitators to maintain permits to cover these same species, as well as mammals and other species (reptiles, amphibians, and fish) considered threatened or endangered at the state level. Veterinarians interested in obtaining federal permits can find information regarding the permits on the United States Fish and Wildlife Service website (www.fws.gov). Veterinarians interested in obtaining state rehabilitation licensure should contact their state wildlife and fisheries service.
Wildlife medicine is in its infancy. Because of this, much of what veterinarians do is based on anecdotal or subjective recommendations. With this knowledge, it is important for those veterinarians working with these animals to document their work and disseminate it to others. This information can be disseminated through presentations at local, state, or national wildlife rehabilitation meetings, or published in appropriate bulletins or journals. In our opinion, the knowledge base regarding wildlife medicine, more so than any other aspect of veterinary medicine, would benefit from more active participation by veterinarians.
Veterinarians that publicize an interest in accepting wildlife cases may be surprised by the diversity of cases being presented to their hospitals. In our practices, amphibians, reptiles, birds, and mammals are all routinely presented. Such a diverse caseload requires veterinarians to be adaptive to the different needs of these animals, both in their medical and surgical knowledge and in their ability to meet the rehabilitation needs (e.g., diet, environment) of the patient. Many veterinarians will limit the types of cases presented to their hospitals. Some of the veterinarians we consult with only accept chelonians, whereas others may accept only avian cases. It is important that veterinarians inform wildlife rehabilitators and clients of particular species they exclude from their practices. It would also be helpful to have a list of other veterinarians on hand that do accept those species, so that those individuals can be referred to an appropriate facility.
When veterinarians accept wildlife cases into their hospitals, it is important that they have buy-in from their staff. Wildlife cases can require a significant amount of time and effort, especially orphaned animals. Therefore, it is often the veterinary staff that will have the most contact with the wildlife cases. Veterinarians that accept these types of cases on a moderate to large scale would certainly benefit from providing at least some of their staff an opportunity to obtain continuing education in wildlife rehabilitation. Many of these opportunities can be obtained from local or state meetings, although the large national meetings (e.g., the annual conferences of the National Wildlife Rehabilitators Association and the International Wildlife Rehabilitators Association) provide the most diverse training opportunities. Membership in these organizations is also highly recommended, as they publish regular bulletins or journals and provide a real resource of potential personal contacts.
It is important that veterinarians train their staff to avoid becoming emotionally attached to their wildlife patients. In our opinion, this is the single most controversial issue that can arise in a hospital. If staff members (and veterinarians) become emotionally attached to their cases, they are less likely to maintain an objective outlook on their cases. It is important to always approach these cases with a triage mentality (Figure 19-1). The time spent treating these patients should also be limited to necessary contact only. Animals that become habituated to humans in captivity may be at greater risk of reinjury or death after release if they lose their fear of humans. For orphaned animals, imprinting is a major concern. Imprinting occurs when an animal recognizes a human as the “parent” animal. Imprinting can potentially lead to dangerous encounters for humans and wildlife, especially with mesopredators, carnivores, and raptors. For this reason, it is important that only trained staff manage orphaned animals.
Figure 19-1 This barred owl presented with a degloving injury over the entire antebrachium. Although the animal was alert, responsive, and eating, it was euthanized because of the extensive tissue necrosis associated with the wound.
When accepting wildlife patients into a hospital, veterinarians must maintain a complete record for each patient. We have found that staff can prove invaluable for this task. The following information should be collected for each patient: the species, age (if known or adult/juvenile), gender (if known), date of presentation, location and date found, type of injury, medical treatment provided (if any), diet and husbandry provided (if any), and name and contact information of the person(s) presenting the animal. Each patient should also be thoroughly evaluated daily and the data recorded using a standard format (SOAP: subjective, objective, assessment, plan). Maintaining this information in a computer database will allow for routine review and analysis of the data. This information can then be used to develop reference ranges for a particular species or area and can be published and presented to a wider audience.
Most of the medical and surgical equipment required for wildlife patients is already available in veterinary hospitals that treat domestic species. However, if a practice is primarily based on domestic species, there may be some specialty equipment that needs to be obtained. A list of different equipment we consider important can be found in Box 19-1.
Incubators are thermostat-controlled microhabitats for small mammals, birds, reptiles, and amphibians. These enclosures should be capable of providing a range of environmental temperatures (80°–100°).
Veterinarians that accept wildlife cases into their practices must be prepared to house a variety of species. It is always best to house wildlife separately from domestic species, to minimize the likelihood of interspecies disease dissemination; however, when this is not possible, all attempts should be made to minimize transmission (e.g., wear gloves, clean cages with separate sponges). The following are some recommendations for housing different wildlife species.
The most difficult aspects of providing housing for small birds is preventing escape and providing security. Using a room that can be darkened will facilitate capture of escapees. Mesh or metal used to cover a cage must have a small diameter to prevent escape. It can also be important to have the enclosure open into a room that will allow for ease of capture (e.g., low ceilings, few hiding spots) should the bird escape the primary cage. The setup of feeding and water stations will vary greatly depending on the species.
For short-term housing, any container, such as a dog or cat kennel, is sufficient. Because pigeons and doves are reservoirs for various avian pathogens, it is always best to isolate them from other species to limit the potential for disease transmission. For longer periods in captivity, these birds may be best housed in an aviary.
Principles of short-term and long-term housing are the same for these birds as was described for pigeons and doves, although the size of the cage may need to be increased for larger specimens. No perching materials need to be provided for short-term housing but should be provided if the bird is kept for a longer period of time to allow roosting at night.1 Substrate should be easily disinfected, to prevent foot disease (e.g., Astroturf is a good substrate).
For short-term waterfowl care, the principles are the same as with those previously mentioned, with the exception of providing water in a container large enough for the bird to stand in. For long-term care, adequate housing will require the addition of a large pool or pond, which may not be feasible in a general practice setting.
Short-term housing for waders should be tall enough to enable the animal to stand naturally. The cage should also be kept dark and quiet with moist, nonslip flooring (e.g., moist sand or newspaper).2 Water should be provided in a shallow container. For long-term housing, a shallow pond or pool and suitable natural cover should be provided. As with waterfowl, this may be difficult for general practitioners to provide.
Seabirds have special requirements in captivity that may make rehabilitation difficult, especially for beginners. Some species of seabird are gregarious and do better when housed in groups. Seabirds are sensitive to sudden noises and should be kept in a quiet environment. A soft substrate that is easy to clean, such as Astroturf, rubber mats, or deep layers of wood shavings, should be used. Animals left on firm substrates (metal flooring or concrete) can develop pododermatitis. Straw or hay bedding should never be used, as they can be a source of fungal spores. It is important to provide ample ventilation to minimize the risk of respiratory disease. For stable patients in medium- to long-term captivity, a water source (e.g., pool or pond) must be provided. This water source should be cleaned regularly to prevent autoinfection.
All of the general principles for housing apply to raptors. In addition, it is extremely important to provide an environment that will prevent any self-induced trauma. Raptors are prone to damaging their feathers, wings, talons, and cere in captivity. Injuries to any of these body parts can delay the rehabilitation process and should be avoided at all costs. The best cage materials to use for housing raptors are those that do not bend or damage the feathers. Because most veterinary hospitals maintain chain-link fence kennels or stainless steel cages, housing for raptors may be limited. Covering the cage with a soft mesh can help diminish the amount of feather damage done to hospitalized raptors. Tailguards made out of old radiograph film can be used to reduce tail feather damage. Perches can also be used to help limit the amount of damage done to the tail feathers. The perch should be positioned so that the tail feathers do not touch the base of the cage and the flight feathers have minimal contact with the sides of the cage. For extended hospitalization, raptors should be housed in an appropriately sized aviary. Whereas groups of some species can be housed together, mixing raptors is not recommended. As with short-term housing, care must be taken that the animal cannot injure itself. An easily disinfected substrate, such as Astroturf or gravel, can be used for the aviary. Multiple perches should be provided. If the bird is not a solid flier, the perches should be maintained close to the ground. Covering the perches with a rough surface (e.g., Astroturf) will minimize the likelihood of a bird developing pododermatitis. Multiple diameter and textured perches should be placed in the cage; however, the diameter should not be so small that the talons puncture the plantar surface of the foot.3 The perches should be cleaned regularly to minimize the likelihood of fecal contamination. As with other species, hay or straw should not be used because of the potential for exposure to Aspergillus spp. spores. Certain species, such as owls, will benefit from shelter.
Housing for small rodents must be constructed to withstand aggressive chewing and escape. For adult rodents, wood, some plastics, and aluminum caging materials are not recommended. Galvanized or stainless steel are more appropriate, as they can handle chewing and are easier to disinfect. For short-term housing, adult rodents can be housed in stainless steel hospital kennels. It is important, of course, that the width of the bars be narrow enough to prevent escape. Within the enclosure, a nest box should be provided, which can be made from wood or cardboard. Recycled newspaper is a suitable substrate. Tree limbs and other natural substances are also recommended and will provide the animals a surface to chew on. Orphaned animals or nonchewing species (e.g., bats) can be housed in clip-top plastic containers. It is important to drill a sufficient number of holes in the container to provide ventilation. Newspaper or towels can be used as a substrate for these cages. For long-term rehabilitation, larger portable cages are recommended. Galvanized wire is probably the least expensive material for constructing these cages. It is best to secure these cages to protect against predation.
Lagomorphs are extremely sensitive and prone to stress, so maintaining a quiet, predator-free environment is essential. Care must be taken to make the enclosure escape-proof. Covering the cage will increase the feeling of security for the animal. Attention to the flooring is also important, as these animals like to dig. A hay bedding or false floor can be used to simulate a burrow. The cage types described for rodents can also be used for lagomorphs.
Mesopredators can be housed in standard domestic animals stainless steel cages; however, this is not without its limitations. Because these cages have swing-doors, it can be difficult to work with these animals if they are fractious. For animals that are difficult to manage, anesthesia is highly recommended. A pole-syringe capable of being inserted between the cage bars can be used to safely deliver an appropriate anesthetic. Shifting these animals to outdoor cages is highly recommended. Chain-link cages can be used to house these animals, but they must be constructed to be escape-proof. Whether inside or outside, the cage should be provided with a shelter box and an area for a latrine.
For short-term hospitalization, fawns can be kept in an isolation area or any area that is away from the noise of humans and other animals. Large deer can be kept for short periods of time in a stable or outhouse with a deep layer of straw. As for the size of the enclosure, a maximum of 1.5 × 1.8 m and 2 × 3 m for fawns and adult deer, respectively, is recommended.4 The enclosure should not have windows, and ventilation should be provided through slats at the top of the walls or ceiling. A door that is divided into a stable-door arrangement, with the top portion only 0.5 m high, is preferred. It is best if the door can be swung inward, so that it can be used as a restraint device for the deer. The top portion of the door should be opened for access only from above. Deer will leap toward light when the door is opened, making other arrangements dangerous. Deer who will be kept in captivity for longer periods of time should be transferred to an experienced rehabilitator who has appropriate pens.
The housing needs of reptiles and amphibians will vary greatly depending on species. Some examples of reptile groupings by environment include those that are aquatic, semiaquatic, arboreal, or terrestrial. Of the terrestrial reptiles, subgroups include those that are fossorial (burrowing), thigmotactic (prefer to wedge themselves into rocky crevices when not basking), and those that live on the surface of the soil. Reptiles can also be grouped according to the time of day that they are active: diurnal, nocturnal, and crepuscular (active during dusk or dawn). Species habits must be known before appropriate housing can be provided. Reptiles kept in inappropriate environments can develop a variety of conditions that will delay the rehabilitation process. For example, terrestrial species kept in moist cages may develop integumentary disease, whereas aquatic species housed in dry habitats will become dehydrated. Arboreal reptiles must be provided with branches, reptiles adapted to saline or brackish water should be furnished with water of the appropriate salinity, fossorial species must be provided substrate to burrow in, and secretive reptiles must be provided hiding places. Water should be provided in the form in which the animal is used to imbibing it. Many lizards drink from rain or dewdrops on foliage and will not drink from dishes. Tortoises should be provided with a shallow bowl of water. For additional information regarding the specific husbandry needs of reptiles, see the appropriate chapters in this text.
Quarantine is an important consideration when practicing wildlife medicine in a domestic species veterinary hospital. Unfortunately, most veterinary hospitals are not built with quarantine in mind. Because wildlife can harbor various bacterial, fungal, viral, and parasitic diseases that can be transmitted to domestic pets, it is important to minimize and restrict both direct and indirect contact between these animals. Wildlife should be housed in a separate room from domestic species. A room with its own ventilation system is preferred. The traffic through the wildlife ward should be one-way. A foot bath with a disinfectant (e.g., sodium hypochlorite) should be placed outside the doorway and used after exiting the room to minimize the likelihood of tracking infectious diseases throughout the hospital. The disinfectant should be changed daily, or as often as needed, to minimize the amount of organic debris in the solution. Organic debris renders many disinfectants useless. Laboratory coats, or preferably jumpsuits that totally cover clothing, should be placed in the wildlife ward and worn when working with the animals. These clothing materials should be taken out of the room only for washing. Any materials being removed from the ward should be placed in a garbage bag and carried through the hospital in these bags to minimize the likelihood of disseminating disease through the hospital. A hand-washing station should be placed within the room. Signs should be posted on the wildlife ward door to alert staff and clients about the presence of wildlife and the need to maintain a strict quarantine protocol.
Zoonotic diseases should always be a concern for those individuals working with wildlife, as many of these animals can harbor a variety of bacterial, viral, fungal and parasitic zoonotic agents (Box 19-2). Because of this, children and individuals with compromised immune systems should not be allowed to work with wildlife. Staff should not be allowed to eat, drink, or smoke near any wildlife patients, and food and drink items should not be allowed near any of the places where diagnostic samples are held. We strongly recommend wearing examination gloves when handling wildlife. Wearing gloves will help minimize the likelihood of introducing pathogens into cuts or abrasions on practitioners’ and staff’s hands. For those cases where an aerosolized pathogen is suspected, a protective mask and eyeglasses should be worn. Individuals who develop an illness after working with wildlife should be examined by a health care specialist immediately. Zoonoses and Communicable Diseases Common to Man and Animals (ed 3), coedited by P. N. Acha and B. Szyfres and published by the Pan American Health Organization (Washington DC), is an excellent reference for obtaining additional information on zoonotic diseases associated with wildlife.
When wildlife cases are presented to a veterinary hospital, they should be considered an emergency. Most of these patients will have injuries that are hours to days old that have limited their ability to obtain food, water, or shelter. Because of these limitations, many of these animals will be dehydrated, cachectic, and possibly hypo- or hyperthermic (seasonally dependent). To increase the likelihood of success with these cases, it is vital that the veterinarian stabilize these patients before pursuing a case diagnosis.
In some emergency situations an animal may present with or develop cardiac or respiratory failure during a course of treatment. Veterinary staff should determine beforehand the level of response they will provide in these cases. If the clinic adheres to a strict triage protocol, then most cases of cardiac or respiratory failure will not be treated. If the clinic does attempt to resuscitate these animals, then the staff should be prepared for a low success rate (<5%).
The first steps to performing cardiopulmonary resuscitation are to intubate the patient and initiate cardiac compressions. In most birds and reptiles, the glottis is located at the base of the tongue and can be easily visualized and intubated (Figure 19-2). The choice of endotracheal tube should be commensurate with the animal’s tracheal diameter. For small species, intravenous catheters (14- to 16-gauge) may be modified into an endotracheal tube. Because birds, crocodilians, and chelonians have complete tracheal rings, the cuff on their endotracheal tube should not be insufflated. In mammals, the intubation procedure can be more difficult, especially in rabbits; however, a laryngoscope or endoscope can be used to assist with intubation. In those cases where intubation is difficult, if not impossible, the animal should be masked and a high flow of oxygen provided. The success rate for animals that cannot be intubated will be less than 1%. Respirations can be given every 5 to 30 cardiac compressions.
Cardiac compressions in wild mammals can be done using the same technique described for domestic mammals. The animal should be placed into lateral recumbency for the procedure. In mammals, the heart is generally located at the point of the elbow. Mustelids are an exception to this rule, with the heart being located more caudally in the thorax. Cardiac compressions can be done by placing the palm of the hand on the lateral surface of the rib cage and compressing ventrally or by grasping the ventral thorax in between the fingers and thumb (fingers on the down side and thumb on the upside of the thorax) and compressing the heart. Cardiac compressions should be done continuously. In birds, chest compressions can be done by pressing the keel. This technique allows for the heart to be compressed by being trapped between the spine and keel. For snakes and lizards, the heart can be directly massaged between an index finger and thumb. In chelonians, cardiac compressions are not possible.
Emergency drugs are an important component of the treatment of cardiac and respiratory failure. Epinephrine should be given when the animal has asystole. The drug can be delivered via a central line, the trachea, or directly into the heart. Multiple doses may be required. In cases where the heart begins beating but remains bradycardic, atropine can be given. Atropine can also be given via a central line, the trachea, or the heart. Doxapram is generally given to stimulate breathing. Different groups of animals appear to respond differently to this drug. The same injection routes may be used for this drug, and it may need to be administered multiple times.
The first step in stabilizing emergency cases with acute hemorrhage is to provide hemostasis. Sutures, radiosurgery, tissue glue, and bandages can all be used to control hemorrhage in the wildlife patient. Once the patient is stabilized, the veterinarian should estimate the volume of blood lost and provide an appropriate replacement fluid. Evaluating a packed cell volume immediately after an acute hemorrhaging event may have limited value. In most cases, it is best to evaluate the packed cell volume 18 to 24 hours after presentation.
Animals presenting with respiratory distress represent a true emergency. In many cases, animals will go into respiratory arrest after only minimal handling. To increase success with these cases, it is often best to restrict handling and allow the animal time to compensate. Placement of the animal into a covered oxygen cage will allow the patient time to stabilize its oxygen levels (if it is going to stabilize). Animals can also be given oxygen directly through a mask, although restraining the animal to deliver the oxygen may be stressful. Once the animal has compensated, then an exam and series of diagnostic tests can be pursued.
The body temperature of a patient can provide a significant amount of information regarding its physiologic status. Although birds are endotherms, there are times when the provision of supplemental heat is important. Birds that fluff their feathers do so to maintain body heat. Birds displaying this behavior must convert energy to maintain their core body temperature. To confirm this, the animal’s body temperature should be taken. Birds naturally maintain a higher body temperature than mammals, with most birds falling between 104° F and 108° F. Because birds with an illness must conserve energy, it is important that veterinarians provide supplemental heat to minimize the energy expenditure associated withheat conservation. Temperature-controlled incubators provide an excellent method of providing a consistent environmental temperature (Figure 19-3). Heating pads, hot water bottles, and incandescent lights can also be used to provide supplemental heat, but all should be monitored closely. Adult birds that are hypothermic can be maintained in an environmental temperature of 82° F to 88° F, whereas juvenile birds may need to be kept warmer depending on the extent of their feather coverage (e.g., nestling vs. fledgling). Mammals, like birds, are also endothermic, and although they can control their own body temperature, they may require supplemental heat on occasion. Mammals that are hypothermic may shiver, have cold extremities, and have a body temperature below the acceptable reference range. Most mammalian body temperatures are between 100° F and 104° F. Opossums are an exception, generally having a body temperature between 92° F and 96° F. Reptiles are ectotherms and depend on their environmental temperature to regulate their core body temperature. For North American reptiles, a temperature range of 80° F to 90° F is appropriate.
Fluid therapy should be provided next. The volume of replacement fluids required for a patient can be calculated by determining the maintenance rate of fluids for a day and degree of dehydration. A list of maintenance fluid rates for different types of wildlife is found in Table 19-1. The techniques used to assess dehydration can be found in Table 19-2. Fluids should always be warmed to the patient’s physiologic temperature before being administered. Identifying which fluid is most appropriate will be based on the type of dehydration. Most wildlife cases present with isotonic dehydration, so a balanced fluid (e.g., 0.9% saline, lactated Ringer’s solution) can be used. Calculating the patient’s osmolality is the best method for estimating the type of dehydration. Laboratories using osmometers can calculate this number; however, if submitting a sample is not possible, then an estimate can be made using the following mathematical formula: OsM = 2(sodium + potassium) + urea + glucose. For reptiles and birds, uric acid can be used as a substitute for urea; however, it may underestimate the true osmolality. A fluid deficit in a mammalian patient can be corrected within 24 to 36 hours, whereas in birds and reptiles, it may take 48 and 96 hours, respectively.
|Group||Suggested maintenance fluids|
|Percentage dehydrated||Clinical signs|
|5%||Some loss of skin turgor|
|Skin slow to return after tenting (2-3 sec)|
|Some tackiness in mucous membranes|
|Capillary refill time (<2 sec)|
|7%-8%||Moderate loss of skin turgor|
|Skin slow to return after tenting (3-5 sec)|
|Ropy mucus in oral cavity, dry mucous membranes|
|Capillary refill time (<3 sec)|
|>10%||Significant loss of skin turgor|
|Skin very slow to return after tenting (>5 sec)|
|Significant ropy mucus in oral cavity|
|Capillary refill time (>3 sec)|
|Sunken eyes (loss of retroorbital fat pads)|
Fluids can be delivered to wildlife using the same basic techniques described for domestic pets. Animals that are only mildly dehydrated and have a functional gastrointestinal tract can have fluids delivered per os. Subcutaneous fluids can be used for those patients that are mildly dehydrated but have some gastrointestinal disease (e.g., diarrhea, vomiting). For moderately dehydrated reptile and mammalian patients, fluids can be given intracoelomically or intraperitoneally, respectively. Because birds have air sacs, they should never be given fluids intracoelomically. For moderate to severe dehydration, fluids should be given intravenously (Figure 19-4) or intraosseously.
Fractures should be stabilized to minimize the risk of further injury to the patient and to control pain. Depending on the site and nature of the fracture, various emergency bandaging methods can be employed. We generally immobilize wing fractures with a figure-of-eight splint (Figure 19-5) or a body wrap. The figure-of-eight splint is appropriate for fractures distal to the elbow, and a body wrap is recommended when the fracture includes the humerus. Vet-wrap (3M Corp., St. Paul, MN), or another comparable bandage material, can be used. For small birds (e.g., hummingbirds), placing the wings in a normal position and taping the primaries where they cross can provide an adequate splint. When immobilizing the wings of a bird, it is important to change the bandage and provide physical therapy every 3 to 4 days. This will prevent excessive contraction of the patagial tendon and atrophy of the muscles. We prefer to replace the bandage under anesthesia, as this minimizes the likelihood of the animal reinjuring itself and controls the pain associated with the procedure. In birds, fractures of the legs can be immobilized with modified syringe-case splints, tape splints, a ball bandage, or a Robert Jones–type splint. Syringe case splints are best suited for fractures distal to the stifle. Tape splints can be used to stabilize toes or the distal leg of a passerine or other lightweight bird. We generally use white, porous tape for these splints. For mammals, limbs can be splinted using the standard techniques described for domestic mammals. Fractures of the reptile limb can be immobilized by taping the limb to the animal’s body. In lizards, a forelimb can be secured against the body wall using porous tape while the rear leg can be immobilized against the tail. In chelonians, the limb can be reduced into a normal position within the shell and taped into place. When splinting any limb, it is important to always immobilize the joint above and below the fracture site.
Wound management should be initiated to limit the amount of fluid or moisture lost from the break in the integument and to limit wound contamination. There are a variety of methods that can be used to manage a skin wound in a wildlife patient. The first and most important step to managing a wound is to remove any necrotic tissue. If necrotic tissue is left behind, it will delay the healing process. Sharp dissection of the wound should be done to remove all of the necrotic tissue. Wound disinfection can be done by irrigating the wound with dilute chlorhexidine, Betadine, or 50% dextrose. We have used the hyperosmotic dextrose, with excellent results. Others report similar results with honey. After disinfection, the wound should be rinsed with a warmed sterile saline. Once disinfected, the wound should be protected against additional contamination. Silver sulfadiazine, or another topical antimicrobial, can be applied to the wound to protect it against opportunistic pathogens and to maintain the hydration of the exposed tissues. Bandage material can be applied to the wound if additional protection is required. A wet-to-dry bandage can be applied to any wound that requires decontamination. Depending on the size of the wound, either 2″ × 2″ or 4″ × 4″ gauze pads can be used for the bandage. The first 4 to 5 gauze pads should be irrigated with sterile saline or a disinfectant, such as chlorhexidine. The gauze pads should be wrung out before being applied to the wound. An additional 4 to 5 dry gauze pads should be placed on top of the moistened pads. All of the gauze should be secured to the wound with Vet-wrap. The bandage should be changed daily. Any necrotic tissue should be removed in between bandage changes. While uncovered, the wound should be disinfected using the technique described previously. The wet-to-dry bandage should be used only until the wound is considered disinfected. Prolonged use of this bandage can lead to tissue desiccation.
Once fluid therapy is initiated, chemotherapeutics can be given. It is important to wait on certain drugs until after fluid therapy has been instituted. For example, the administration of steroidal antiinflammatories could have a negative response if given to a dehydrated patient. A variety of chemotherapeutics are available to the veterinarian, including antiinflammatories (steroidal and nonsteroidal), analgesics, antibiotics, antifungals, antivirals, anesthetics, antiemetics, chelating agents, vitamins, and minerals. A list of common drugs used to treat wildlife can be found in Table 19-3.
|Atropine||0.5 mg/kg||IV, IO, IT|
|Diazepam||0.5-1.0 mg/kg||IV, IO|
|Doxapram||20 mg/kg||IV, IO, IT|
|Epinephrine||0.5-1.0 mg/kg||1 : 1,000; IV, IO, IT|
|Amikacin||3-5 mg/kg||Reptiles: IM, q72h|
|15-20 mg/kg||Birds: IM, q24h|
|2.5-10 mg/kg||Mammals: IM, q12-24h|
|Amoxicillin||10-30 mg/kg||Reptiles: PO, IM, q12-24h|
|100 mg/kg||Birds, PO, q12h|
|10-20 mg/kg||Mammals: PO, q12h; NOT recommended for rodents or lagomorphs|
|Cephalexin||20-40 mg/kg||Reptiles: PO, q12h|
|100 mg/kg||Birds, PO, q12h|
|15-30 mg/kg||Mammals: PO, q12h; NOT recommended for rodents or lagomorphs|
|Ceftazidime||20 mg/kg||Reptiles: IM, q72h|
|Ciprofloxacin||10 mg/kg||Reptiles: PO, q24h|
|15 mg/kg||Birds: PO, q12h|
|15 mg/kg||Mammals: PO, q12h|
|Doxycycline||5-10 mg/kg||Reptiles: PO, q24h|
|25-100 mg/kg||Birds: PO, q24h|
|Enrofloxacin||5-10 mg/kg||Reptiles: PO, q24h|
|10-15 mg/kg||Birds: PO, q12h|
|5-10 mg/kg||Mammals: PO, q12h|
|Tetracycline||200 mg/kg||Birds: PO, q12-24h|
|20 mg/kg||Mammals: PO, q12h; use with caution in lagomorphs and rodents|
|Trimethoprim-sulfadiazine||15-30 mg/kg||Reptiles: PO, q24h|
|50-75 mg/kg||Birds: PO, q12-24h|
|5-25 mg/kg||Mammals: PO, q12-24h|
|Itraconazole||5-10 mg/kg||Reptiles: PO, q24-48h; monitor for neurologic disease|
|2.5-10 mg/kg||Birds: PO, q24h; monitor for neurologic disease|
|2.5-5 mg/kg||Mammals: PO, q24h; monitor for neurologic disease|
|Ketoconazole||25-50 mg/kg||Reptiles: PO, q24h|
|20-50 mg/kg||Birds: PO, q12-24h|
|20-50 mg/kg||Mammals: PO, q24h|
|Nystatin||100,000 IU/kg||Reptiles: PO, q24h|
|100,000-300, 000 IU/kg||Birds: PO, q12h|
|Fenbendazole||25-100 mg/kg||Avian, reptiles: PO, once, repeat 10-14 days|
|5-10 mg/kg||Mammals: PO, q24h × 3-5 days|
|Ivermectin||0.2-0.4 mg/kg||All wildlife: IM, PO; Do not use in chelonians|
|Metronidazole||25-50 mg/kg||Reptiles: PO, q24-48h|
|20-40 mg/kg||Birds: PO, q12-24h|
|15-25 mg/kg||Mammals: PO, q12-24h|
|Praziquantel||5-8 mg/kg||Reptiles: IM, repeat 10-14 days|
|20-40 mg/kg||Birds: PO, q12-24h|
|5-10 mg/kg||Mammals: IM, repeat 10-14 days|
IM, Intramuscular; IO, intraosseous; IT, intratracheal; IV, intravenous; PO, per os.
Most injured wildlife cases will be transported to a veterinary clinic by the public, but there may be times when veterinarians are in a situation that requires them or their staff to capture an animal or give counsel on appropriate capture and transport to a member of the public. The techniques vary according to the species being approached, but some generalities apply. If observing the animal before capture, it is best to evaluate its posture and attitude from a distance (e.g., alert, depressed, lethargic). This information can be used to develop a capture strategy. Animals that are depressed and lethargic should be approached cautiously, as they may be more susceptible to sudden death or capture myopathy. When developing a capture strategy, it is also imperative to consider the humans involved with the procedure, to ensure no harm comes to those involved. Before capture, identify the major “weapons” an animal will use to defend itself. Raptors, for example, may use their talons and beak as weapons.
An appropriate-sized, darkened cardboard box (with ventilation holes cut in) or pet carrier that opens from the top can be used to transport wildlife. The cardboard box is an excellent transport carrier because it can be discarded after use; the pet carrier can be disinfected between uses. Homemade wooden boxes may also be used but are more difficult to disinfect. It is important to include a nonslip floor covering in the transport container to ensure proper footing in the transport box. Noncovered cardboard surfaces have been associated with the development of splay leg and bilateral partial paresis in some bird species.5 When transporting birds, it is imperative that the box be large enough that the bird can turn without damaging its feathers. When flight or tail feathers are damaged, it can increase the rehabilitation time for a patient.
Small and medium-sized birds, including songbirds, pigeons, doves, and crows, pose few physical risks to humans, although the larger birds in this group can deliver painful bites or scratches. These animals are best captured using a small diameter hole net or cloth. A cloth sack may be used if no box is available for transport.
Gamebirds are notorious for biting and scratching. These birds are generally good runners and will often run toward the thickest cover available, making capture difficult. Because gamebirds are generally high-strung, they may be injured by the inexperienced handler. Several people may be needed to flush a bird under cover. A net or towel is preferred for capturing these animals. Once the bird is captured, it is best to keep the box covered (darkened) to minimize the stress associated with transport.
Waterfowl, including ducks, geese, and swans, can deliver very painful bites and scratches. In addition, swans can also cause injury by striking with their wings. During the capture process, it is important to prevent these animals from reentering the water. Some form of water transportation and expert assistance may be necessary if the birds are in the water. Specialized equipment, such as swan hooks and bags, may also aid in capture and transport. The easiest method for transporting these animals is to place them in a transport carrier or blanket or sack.
Many of the wading species have razor-sharp pointed beaks, and they will use them to stab at the faces of any perceived predators (including humans). Appropriate eye protection, such as safety goggles, should always be worn when handling these birds. Capture is similar to that of waterfowl. Transport boxes should be tall enough that the bird can stand comfortably. If such a box is not available, short trips can be made with the bird wrapped in a towel or blanket and the legs extended behind the bird. Care must be taken that the head is always sufficiently restrained.
The main danger posed by seabirds is from their beaks, which they may use to bite or stab at the face. Some seabirds also have sharp claws, which are capable of causing deep lacerations. As with waders, safety goggles should be worn and the bird never restrained close to the face. If the species in hand has internal nares, be careful not to hold the beak closed because it can affect normal respiration. These birds will also attempt to return to the water when they sense danger, so care must be taken to block this route of escape. A net is usually necessary for capture, but a towel or blanket may also be used. The beak can be kept closed by using tape or a rubber band. The head of these animals should be restrained and covered at all times, to prevent injury to the handler and reduce the stress on the animal. A towel can be wrapped around the body of these birds to restrain the wings; however, the towel should not be held so tight that it affects respiration (e.g., keel excursions). Because seabirds commonly regurgitate, it is important to remove any beak restraint before transporting the animal, to prevent aspiration.5 The transportation carrier must be large enough to prevent damage to the flight and tail feathers.
Although the beaks of raptors may look formidable, the biggest threat associated with these birds is their talons. Thick leather gloves, such as welding gloves, should be worn when handling medium to larger-sized specimens. Small raptors may be handled using outdoor work gloves (e.g., cotton or leather). When approached, most raptors roll backward and present their talons. When presented with a bird in this position, it is possible to offer them a towel or blanket to grasp before restraining the legs. The legs should always be grasped as close to the body wall as possible, as this will reduce the likelihood of causing a tibiotarsal fracture or injuries associated with self-taloning. The head of the raptor should be grasped using the same techniques to restrain other birds, with the index finger and thumb positioned under the mandible (Figure 19-6). For animals that are free-ranging, a bal chatri trap may be used. These traps can be built out of wire mesh (e.g., chicken wire) and fishing line. The wire mesh is first used to construct a wire cage to hold a live prey species (e.g., pigeon or rodent). A second piece of chicken wire is then placed over the prey cage, thus preventing injury to the prey species. The fishing line is then cut into small pieces (6-8 cm) and tied into small nooses. These nooses are secured over the entire surface of the trap. When the raptor attacks the trap, it becomes entangled in the trap and cannot lift off the ground with the trap.
Unconscious mammals must be approached and handled with caution, as they may suddenly regain consciousness. Mammals should only be carried in an appropriate transport container and should never be captured or handled with unprotected hands. For capture, a towel or blanket may be placed over the animal to reduce its vision. Large and potentially dangerous mammals should always be sedated before being transported.
These animals frequently bite when handled. Leather gloves should always be worn by the individual capturing the animal to reduce the risk of injury and disease transmission. Small wild mammals may be caught with small nets or by covering them with a towel or blanket. Transport boxes for these animals should be escape-proof. Because of their ability to chew through cardboard, sturdy plastic or fine-meshed wire carriers are strongly recommended.
Although considered docile by many, lagomorphs may bite and scratch during capture and handling. Leather gloves should be worn to reduce the risk of injury. Rabbits and hares are more susceptible to the effects of stress than most other species. The short-term effects associated with stress may be manifested in sudden death due to heart failure or fatal oliguria.6 Over longer periods of time, stress may be manifested as reduced gut motility and the disrupted carbohydrate metabolism, leading to diarrhea, hepatic lipidosis, liver failure, and death. In these cases, the cecal microflora are also disrupted, leading to enterotoxemia and gut stasis. Lagomorphs are also prone to spinal injury during capture and handling.6 Blankets, towels, or nets may be used to capture animals that are free-ranging.
Mesopredators have very sharp teeth and can deliver a painful bite, even through leather gloves. Animals that are severely ill or in shock may appear tame but can still inflict a serious injury. It is important to know that opossums can climb upward when held by their tail. Mesopredators may be caught in a net and then pinned using a soft-headed broom. Once pinned safely, they can be scruffed. If this method does not work, a quick-release rabies pole can be used. It is preferable to use one with a rubber end to prevent fracturing an animal’s teeth as is bites the pole.7 Inexperienced individuals should not attempt to capture these animals, as they are likely to injure both the animal and themselves. A live animal trap, plastic domestic pet travel carrier, or sturdy plastic trash can with a tight-fitting lid can be used to transport mesopredators.
Yearling and adult deer can pose a special danger. These animals are capable of gouging with their antlers or kicking with their feet. Only trained professionals should attempt to capture an injured subadult or adult deer. A deer that is severely injured or in shock may appear tame when approached; however, they are still capable of quick bursts of speed and energy and can injure an inexperienced handler. Before approaching an injured deer, it should be evaluated from a distance to determine its general status. The equipment generally used to capture deer include dark towels or drapes for covering the head, thick blankets, soft ropes, soft cargo or freight netting, and possibly a dart gun or pole-syringe.4 Anesthetics appropriate for sedating deer and a euthanasia solution should be kept on hand. If the deer is trapped in fencing or some other physical structure, it should be sedated remotely to prevent further injury to the deer. Expert assistance should also be sought for transport of injured deer. Individual deer should never be transported loose within a trailer without restraint. Large deer can best be transported wrapped up in cargo nets with the eyes blindfolded and the feet hobbled. Small deer can be wrapped in blankets. Trussed-up deer can be transported in a vehicle or trailer.
Fawns should be captured by hand and restrained manually. The deer should be approached from behind, and if recumbent, covered with a blanket, net, or coat. Many fawns do not display any resistance to capture. Once restrained, the animal should be blindfolded to reduce its stress levels. Once masked, these deer will lie quietly if they are undisturbed. The animal’s legs can be tied together at the level of the metacarpi and metatarsi (cannons) using a soft rope; however, hobbling an animal in this way must be done carefully so that the soft ropes are not too tight. To prevent further struggling, the deer should then be trussed up in a blanket or cargo net and secured with additional ropes. Some deer are very vocal when caught, injured, or handled.
Expert assistance should be sought before attempting to capture and transport venomous snakes. For nonvenomous snakes and other reptiles, a cloth or canvas bag placed in a solid box makes an ideal transportation container. Amphibians can be moved in a similar manner, although the transport bag should be kept moist to prevent desiccation. This can be achieved by placing damp vegetation, such as sphagnum moss, in the bag or frequently misting the bag with dechlorinated water.
Once the animal is transported to the clinic, the veterinary staff should be prepared to restrain and handle the animal for the physical examination and any diagnostic testing procedures. It is essential that the staff be trained properly to minimize the likelihood of injury to the human handler and patient. Restraint and handling is a stressful time for the patient, often leading to elevated cortisol or corticosterone production. Over time, this physiologic stress could have detrimental effects on the patient, including a reduction in metabolism, immune function, and normal behaviors.
For most simple procedures, physical restraint alone can be used. Most species are easier to catch and handle in low light conditions and can be calmed by covering their head. At our hospitals, a towel is often used to support the body, restrain the wings, and cover the head. If the animal is not stable enough for chemical anesthesia during radiography, tape and a plexiglass board can be used to restrain the animals. In all cases of restraint, special care must be taken to ensure that the animal can have normal keel excursions that allow for adequate ventilation, as birds lack a diaphragm. Most birds will attempt to beat their wings during restraint, and this must be prevented for several reasons: They (1) risk damaging their flight and tail feathers, (2) can fracture the bones of their wings, (3) can worsen any injury, and (4) risk expending valuable energy in the process. When the wings are immobilized, they should be placed into their normal resting position.
The simplest and most effective method of restraint is to place the bird in one hand with the dorsum of the bird in the palm and the neck held gently between the forefinger and second finger. It is especially important in the handling of small birds that undue pressure is not exerted that may inhibit respiration.